Photoresist developer and method of developing photoresist

ABSTRACT

A photoresist developer includes a solvent having Hansen solubility parameters of 15&lt;δ d &lt;25, 10&lt;δ p &lt;25, and 6&lt;δ p &lt;30; an acid having an acid dissociation constant, pKa, of −15&lt;pKa&lt;4, or a base having a pKa of 40&gt;pKa&gt;9.5; and a chelate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/585,255, filed Nov. 13, 2017, the entire disclosure of which isincorporated herein by reference.

TECHNICAL FIELD

The disclosure relates to a photoresist developer compositions andmethods of developing photoresists used in semiconductor manufacturingprocesses.

BACKGROUND

As consumer devices have gotten smaller and smaller in response toconsumer demand, the individual components of these devices havenecessarily decreased in size as well. Semiconductor devices, which makeup a major component of devices such as mobile phones, computer tablets,and the like, have been pressured to become smaller and smaller, with acorresponding pressure on the individual devices (e.g., transistors,resistors, capacitors, etc.) within the semiconductor devices to also bereduced in size.

One enabling technology that is used in the manufacturing processes ofsemiconductor devices is the use of photolithographic materials. Suchmaterials are applied to a surface of a layer to be patterned and thenexposed to an energy that has itself been patterned. Such an exposuremodifies the chemical and physical properties of the exposed regions ofthe photosensitive material. This modification, along with the lack ofmodification in regions of the photosensitive material that were notexposed, can be exploited to remove one region without removing theother, or vice-verse.

However, as the size of individual devices has decreased, processwindows for photolithographic processing has become tighter and tighter.As such, advances in the field of photolithographic processing arenecessary to maintain the ability to scale down the devices, and furtherimprovements are needed in order to meet the desired design criteriasuch that the march towards smaller and smaller components may bemaintained.

As the semiconductor industry has progressed into nanometer technologyprocess nodes in pursuit of higher device density, higher performance,and lower costs, there have been challenges in reducing semiconductorfeature size.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 illustrates a process flow of manufacturing a semiconductordevice according to embodiments of the disclosure.

FIG. 2 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 3 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 4 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 5 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 6 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 7 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 8 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 9 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 10 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 11 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 12 shows a process stage of a sequential operation according to anembodiment of the disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the disclosure. Specific embodiments or examples of components andarrangements are described below to simplify the present disclosure.These are, of course, merely examples and are not intended to belimiting. For example, dimensions of elements are not limited to thedisclosed range or values, but may depend upon process conditions and/ordesired properties of the device. Moreover, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed interposing the first and second features, suchthat the first and second features may not be in direct contact. Variousfeatures may be arbitrarily drawn in different scales for simplicity andclarity.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The device may be otherwise oriented (rotated 90 degrees orat other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. In addition, the term“made of” may mean either “comprising” or “consisting of.”

FIG. 1 illustrates a process flow 100 of manufacturing a semiconductordevice according to embodiments of the disclosure. A photoresist iscoated on a surface of a layer to be patterned or a substrate 10 inoperation S110, in some embodiments, to form a photoresist layer 15, asshown in FIG. 2. Then the photoresist layer 15 undergoes a first bakingoperation S120 to evaporate solvents in the photoresist composition insome embodiments. The photoresist layer 15 is baked at a temperature andtime sufficient to cure and dry the photoresist layer 15. In someembodiments, the photoresist layer is heated to a temperature of about40° C. and 250° C. for about 10 seconds to about 10 minutes.

After the first baking operation S120, the photoresist layer 15 isselectively exposed to actinic radiation 45 (see FIG. 3) in operationS130. In some embodiments, the photoresist layer 15 is selectivelyexposed to ultraviolet radiation. In some embodiments, the ultravioletradiation is deep ultraviolet radiation. In some embodiments, theultraviolet radiation is extreme ultraviolet (EUV) radiation. In someembodiments, the radiation is an electron beam.

As shown in FIG. 3, the exposure radiation 45 passes through a photomask30 before irradiating the photoresist layer 15 in some embodiments. Insome embodiments, the photomask has a pattern to be replicated in thephotoresist layer 15. The pattern is formed by an opaque pattern 35 onphotomask substrate 40, in some embodiments. The opaque pattern 35 maybe formed by a material opaque to ultraviolet radiation, such aschromium, while the photomask substrate 40 is formed of a material thatis transparent to ultraviolet radiation, such as fused quartz.

The region of the photoresist layer exposed to radiation 50 undergoes achemical reaction thereby changing its solubility in a subsequentlyapplied developer relative to the region of the photoresist layer notexposed to radiation 52. In some embodiments, the portion of thephotoresist layer exposed to radiation 50 undergoes a crosslinkingreaction.

Next the photoresist layer 15 undergoes a post-exposure bake inoperation S140. In some embodiments, the photoresist layer 15 is heatedto a temperature of about 50° C. and 160° C. for about 20 seconds toabout 120 seconds. The post-exposure baking may be used in order toassist in the generating, dispersing, and reacting of the acid/base/freeradical generated from the impingement of the radiation 45 upon thephotoresist layer 15 during the exposure. Such assistance helps tocreate or enhance chemical reactions which generate chemical differencesbetween the exposed region 50 and the unexposed region 52 within thephotoresist layer. These chemical differences also caused differences inthe solubility between the exposed region 50 and the unexposed region52.

The selectively exposed photoresist layer is subsequently developed byapplying a developer to the selectively exposed photoresist layer inoperation S150. As shown in FIG. 4, a developer 57 is supplied from adispenser 62 to the photoresist layer 15. In some embodiments, theexposed portion of the photoresist layer 50 is removed by the developer57 forming a pattern of openings 55 in the photoresist layer 15 toexpose the substrate 20, as shown in FIG. 5.

In some embodiments, the pattern of openings 55 in the photoresist layer15 are extended into the layer to be patterned or substrate 10 to createa pattern of openings 55′ in the substrate 10, thereby transferring thepattern in the photoresist layer 15 into the substrate 10, as shown inFIG. 6. The pattern is extended into the substrate by etching, using oneor more suitable etchants. The unexposed photoresist layer 15 is atleast partially removed during the etching operation in someembodiments. In other embodiments, the unexposed photoresist layer 15 isremoved after etching the substrate 10 by using a suitable photoresiststripper solvent or by a photoresist ashing operation.

In some embodiments, the substrate 10 includes a single crystallinesemiconductor layer on at least it surface portion. The substrate 10 mayinclude a single crystalline semiconductor material such as, but notlimited to Si, Ge, SiGe, GaAs, InSb, GaP, GaSb, InAlAs, InGaAs, GaSbP,GaAsSb and InP. In some embodiments, the substrate 10 is a silicon layerof an SOI (silicon-on insulator) substrate. In certain embodiments, thesubstrate 10 is made of crystalline Si.

The substrate 10 may include in its surface region, one or more bufferlayers (not shown). The buffer layers can serve to gradually change thelattice constant from that of the substrate to that of subsequentlyformed source/drain regions. The buffer layers may be formed fromepitaxially grown single crystalline semiconductor materials such as,but not limited to Si, Ge, GeSn, SiGe, GaAs, InSb, GaP, GaSb, InAlAs,InGaAs, GaSbP, GaAsSb, GaN, GaP, and InP. In an embodiment, the silicongermanium (SiGe) buffer layer is epitaxially grown on the siliconsubstrate 10. The germanium concentration of the SiGe buffer layers mayincrease from 30 atomic % for the bottom-most buffer layer to 70 atomic% for the top-most buffer layer.

In some embodiments, the substrate 10 includes at least one metal, metalalloy, and metal/nitride/sulfide/oxide/silicide having the formulaMX_(a), where M is a metal and X is N, S, Se, O, Si, and a is from about0.4 to about 2.5. In some embodiments, the substrate 10 includestitanium, aluminum, cobalt, ruthenium, titanium nitride, tungstennitride, tantalum nitride, and combinations thereof.

In some embodiments, the substrate 10 includes a dielectric having atleast silicon, metal oxide, and metal nitride of the formula MX_(b),where M is a metal or Si, X is N or O, and b ranges from about 0.4 toabout 2.5. In some embodiments, the substrate 10 includes silicondioxide, silicon nitride, aluminum oxide, hafnium oxide, lanthanumoxide, and combinations thereof.

The photoresist layer 15 is a photosensitive layer that is patterned byexposure to actinic radiation. Typically, the chemical properties of thephotoresist regions struck by incident radiation change in a manner thatdepends on the type of photoresist used. Photoresist layers 15 aretypically positive resists or negative resists. Conventionally, positiveresist refers to a photoresist material that when exposed to radiation(typically UV light) becomes soluble in a developer, while the region ofthe photoresist that is non-exposed (or exposed less) is insoluble inthe developer. Negative resist, on the other hand, conventionally refersto a photoresist material that when exposed to radiation becomesinsoluble in the developer, while the region of the photoresist that isnon-exposed (or exposed less) is soluble in the developer. The region ofa negative resist that becomes insoluble upon exposure to radiation maybecome insoluble due to a cross-linking reaction caused by the exposureto radiation.

Whether a resist is a positive or negative may depend on the type ofdeveloper used to develop the resist. For example, some positivephotoresists provide a positive pattern, (i.e. —the exposed regions areremoved by the developer), when the developer is an aqueous-baseddeveloper, such as a tetramethylammonium hydroxide (TMAH) solution. Onthe other hand, the same photoresist provides a negative pattern (i.e.—the unexposed regions are removed by the developer) when the developeris an organic solvent. Further, in some negative photoresists developedwith the TMAH solution, the unexposed regions of the photoresist areremoved by the TMAH, and the exposed regions of the photoresist, thatundergo cross-linking upon exposure to actinic radiation, remain on thesubstrate after development. In some embodiments of the presentdisclosure, a negative photoresist is exposed to actinic radiation. Theexposed portions of the negative photoresist undergo crosslinking as aresult of the exposure to actinic radiation, and during development theexposed, crosslinked portions of the photoresist are removed by thedeveloper leaving the unexposed regions of the photoresist remaining onthe substrate.

In an embodiment, the photoresist layer 15 is a negative photoresistthat undergoes a cross-linking reaction upon exposure to the radiation.Photoresists according to the present disclosure include a polymer resinalong with one or more photoactive compounds (PACs) in a solvent, insome embodiments. In some embodiments, the polymer resin includes ahydrocarbon structure (such as an alicyclic hydrocarbon structure) thatcontains one or more groups that will decompose (e.g., acid labilegroups) or otherwise react when mixed with acids, bases, or freeradicals generated by the PACs (as further described below). In someembodiments, the hydrocarbon structure includes a repeating unit thatforms a skeletal backbone of the polymer resin. This repeating unit mayinclude acrylic esters, methacrylic esters, crotonic esters, vinylesters, maleic diesters, fumaric diesters, itaconic diesters,(meth)acrylonitrile, (meth)acrylamides, styrenes, vinyl ethers,combinations of these, or the like.

Specific structures that are utilized for the repeating unit of thehydrocarbon structure in some embodiments, include one or more of methylacrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butylacrylate, isobutyl acrylate, tert-butyl acrylate, n-hexyl acrylate,2-ethylhexyl acrylate, acetoxyethyl acrylate, phenyl acrylate,2-hydroxyethyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethylacrylate, 2-(2-methoxyethoxy)ethyl acrylate, cyclohexyl acrylate, benzylacrylate, 2-alkyl-2-adamantyl (meth)acrylate ordialkyl(1-adamantyl)methyl (meth)acrylate, methyl methacrylate, ethylmethacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butylmethacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-hexylmethacrylate, 2-ethylhexyl methacrylate, acetoxyethyl methacrylate,phenyl methacrylate, 2-hydroxyethyl methacrylate, 2-methoxyethylmethacrylate, 2-ethoxyethyl methacrylate, 2-(2-methoxyethoxy)ethylmethacrylate, cyclohexyl methacrylate, benzyl methacrylate,3-chloro-2-hydroxypropyl methacrylate, 3-acetoxy-2-hydroxypropylmethacrylate, 3-chloroacetoxy-2-hydroxypropyl methacrylate, butylcrotonate, hexyl crotonate, or the like. Examples of the vinyl estersinclude vinyl acetate, vinyl propionate, vinyl butylate, vinylmethoxyacetate, vinyl benzoate, dimethyl maleate, diethyl maleate,dibutyl maleate, dimethyl fumarate, diethyl fumarate, dibutyl fumarate,dimethyl itaconate, diethyl itaconate, dibutyl itaconate, acrylamide,methyl acrylamide, ethyl acrylamide, propyl acrylamide, n-butylacrylamide, tert-butyl acrylamide, cyclohexyl acrylamide, 2-methoxyethylacrylamide, dimethyl acrylamide, diethyl acrylamide, phenyl acrylamide,benzyl acrylamide, methacrylamide, methyl methacrylamide, ethylmethacrylamide, propyl methacrylamide, n-butyl methacrylamide,tert-butyl methacrylamide, cyclohexyl methacrylamide, 2-methoxyethylmethacrylamide, dimethyl methacrylamide, diethyl methacrylamide, phenylmethacrylamide, benzyl methacrylamide, methyl vinyl ether, butyl vinylether, hexyl vinyl ether, methoxyethyl vinyl ether, dimethylaminoethylvinyl ether, or the like. Examples of styrenes include styrene, methylstyrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropylstyrene, butyl styrene, methoxy styrene, butoxy styrene, acetoxystyrene, chloro styrene, dichloro styrene, bromo styrene, vinyl methylbenzoate, α-methyl styrene, maleimide, vinylpyridine, vinylpyrrolidone,vinylcarbazole, combinations of these, or the like.

In some embodiments, the repeating unit of the hydrocarbon structurealso has either a monocyclic or a polycyclic hydrocarbon structuresubstituted into it, or the monocyclic or polycyclic hydrocarbonstructure is the repeating unit, in order to form an alicyclichydrocarbon structure. Specific examples of monocyclic structures insome embodiments include bicycloalkane, tricycloalkane,tetracycloalkane, cyclopentane, cyclohexane, or the like. Specificexamples of polycyclic structures in some embodiments includeadamantane, norbornane, isobornane, tricyclodecane, tetracycododecane,or the like.

The group which will decompose, otherwise known as a leaving group or,in some embodiments in which the PAC is a photoacid generator, an acidlabile group, is attached to the hydrocarbon structure so that, it willreact with the acids/bases/free radicals generated by the PACs duringexposure. In some embodiments, the group which will decompose is acarboxylic acid group, a fluorinated alcohol group, a phenolic alcoholgroup, a sulfonic group, a sulfonamide group, a sulfonylimido group, an(alkylsulfonyl) (alkylcarbonyl)methylene group, an(alkylsulfonyl)(alkyl-carbonyl)imido group, abis(alkylcarbonyl)methylene group, a bis(alkylcarbonyl)imido group, abis(alkylsylfonyl)methylene group, a bis(alkylsulfonyl)imido group, atris(alkylcarbonyl methylene group, a tris(alkylsulfonyl)methylenegroup, combinations of these, or the like. Specific groups that are usedfor the fluorinated alcohol group include fluorinated hydroxyalkylgroups, such as a hexafluoroisopropanol group in some embodiments.Specific groups that are used for the carboxylic acid group includeacrylic acid groups, methacrylic acid groups, or the like.

In some embodiments, the polymer resin also includes other groupsattached to the hydrocarbon structure that help to improve a variety ofproperties of the polymerizable resin. For example, inclusion of alactone group to the hydrocarbon structure assists to reduce the amountof line edge roughness after the photoresist has been developed, therebyhelping to reduce the number of defects that occur during development.In some embodiments, the lactone groups include rings having five toseven members, although any suitable lactone structure may alternativelybe used for the lactone group.

In some embodiments, the polymer resin includes groups that can assistin increasing the adhesiveness of the photoresist layer 15 to underlyingstructures (e.g., substrate 10). Polar groups may be used to helpincrease the adhesiveness. Suitable polar groups include hydroxylgroups, cyano groups, or the like, although any suitable polar groupmay, alternatively, be used.

Optionally, the polymer resin includes one or more alicyclic hydrocarbonstructures that do not also contain a group which will decompose in someembodiments. In some embodiments, the hydrocarbon structure that doesnot contain a group which will decompose includes structures such as1-adamantyl(meth)acrylate, tricyclodecanyl (meth)acrylate, cyclohexayl(methacrylate), combinations of these, or the like.

Additionally, some embodiments of the photoresist include one or morephotoactive compounds (PACs). The PACs are photoactive components, suchas photoacid generators, photobase generators, free-radical generators,or the like. The PACs may be positive-acting or negative-acting. In someembodiments in which the PACs are a photoacid generator, the PACsinclude halogenated triazines, onium salts, diazonium salts, aromaticdiazonium salts, phosphonium salts, sulfonium salts, iodonium salts,imide sulfonate, oxime sulfonate, diazodisulfone, disulfone,o-nitrobenzylsulfonate, sulfonated esters, halogenated sulfonyloxydicarboximides, diazodisulfones, α-cyanooxyamine-sulfonates,imidesulfonates, ketodiazosulfones, sulfonyldiazoesters,1,2-di(arylsulfonyl)hydrazines, nitrobenzyl esters, and the s-triazinederivatives, combinations of these, or the like.

Specific examples of photoacid generators includeα-(trifluoromethylsulfonyloxy)-bicyclo[2.2.1]hept-5-ene-2,3-dicarb-o-ximide(MDT), N-hydroxy-naphthalimide (DDSN), benzoin tosylate,t-butylphenyl-α-(p-toluenesulfonyloxy)-acetate andt-butyl-α-(p-toluenesulfonyloxy)-acetate, triarylsulfonium anddiaryliodonium hexafluoroantimonates, hexafluoroarsenates,trifluoromethanesulfonates, iodonium perfluorooctanesulfonate,N-camphorsulfonyloxynaphthalimide,N-pentafluorophenylsulfonyloxynaphthalimide, ionic iodonium sulfonatessuch as diaryl iodonium (alkyl or aryl)sulfonate andbis-(di-t-butylphenyl)iodonium camphanylsulfonate,perfluoroalkanesulfonates such as perfluoropentanesulfonate,perfluorooctanesulfonate, perfluoromethanesulfonate, aryl (e.g., phenylor benzyl)triflates such as triphenylsulfonium triflate orbis-(t-butylphenyl)iodonium triflate; pyrogallol derivatives (e.g.,trimesylate of pyrogallol), trifluoromethanesulfonate esters ofhydroxyimides, α,α′-bis-sulfonyl-diazomethanes, sulfonate esters ofnitro-substituted benzyl alcohols, naphthoquinone-4-diazides, alkyldisulfones, or the like.

In some embodiments in which the PACs are free-radical generators, thePACs include n-phenylglycine; aromatic ketones, including benzophenone,N,N′-tetramethyl-4,4′-diaminobenzophenone,N,N′-tetraethyl-4,4′-diaminobenzophenone,4-methoxy-4′-dimethylaminobenzo-phenone,3,3′-dimethyl-4-methoxybenzophenone,p,p′-bis(dimethylamino)benzo-phenone,p,p′-bis(diethylamino)-benzophenone; anthraquinone,2-ethylanthraquinone; naphthaquinone; and phenanthraquinone; benzoinsincluding benzoin, benzoinmethylether, benzoinisopropylether,benzoin-n-butylether, benzoin-phenylether, methylbenzoin andethylbenzoin; benzyl derivatives, including dibenzyl,benzyldiphenyldisulfide, and benzyldimethylketal; acridine derivatives,including 9-phenylacridine, and 1,7-bis(9-acridinyl)heptane;thioxanthones, including 2-chlorothioxanthone, 2-methylthioxanthone,2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, and2-isopropylthioxanthone; acetophenones, including1,1-dichloroacetophenone, p-t-butyldichloro-acetophenone,2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenyl acetophenone, and2,2-dichloro-4-phenoxyacetophenone; 2,4,5-triarylimidazole dimers,including 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer,2-(o-chlorophenyl)-4,5-di-(m-methoxyphenyl imidazole dimer,2-(o-fluorophenyl)-4,5-diphenylimidazole dimer,2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer,2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer,2,4-di(p-methoxyphenyl)-5-phenylimidazole dimer,2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer and2-(p-methylmercaptophenyl)-4,5-diphenylimidazole dimmer; combinations ofthese, or the like.

In some embodiments in which the PACs are photobase generators, the PACsincludes quaternary ammonium dithiocarbamates, a aminoketones,oxime-urethane containing molecules such as dibenzophenoneoximehexamethylene diurethan, ammonium tetraorganylborate salts, andN-(2-nitrobenzyloxycarbonyl)cyclic amines, combinations of these, or thelike.

As one of ordinary skill in the art will recognize, the chemicalcompounds listed herein are merely intended as illustrated examples ofthe PACs and are not intended to limit the embodiments to only thosePACs specifically described. Rather, any suitable PAC may be used, andall such PACs are fully intended to be included within the scope of thepresent embodiments.

In some embodiments, a cross-linking agent is added to the photoresist.The cross-linking agent reacts with one group from one of thehydrocarbon structures in the polymer resin and also reacts with asecond group from a separate one of the hydrocarbon structures in orderto cross-link and bond the two hydrocarbon structures together. Thisbonding and cross-linking increases the molecular weight of the polymerproducts of the cross-linking reaction and increases the overall linkingdensity of the photoresist. Such an increase in density and linkingdensity helps to improve the resist pattern.

In some embodiments the cross-linking agent has the following structure:

wherein C is carbon, n ranges from 1 to 15; A and B independentlyinclude a hydrogen atom, a hydroxyl group, a halide, an aromatic carbonring, or a straight or cyclic alkyl, alkoxyl/fluoro, alkyl/fluoroalkoxylchain having a carbon number of between 1 and 12, and each carbon Ccontains A and B; a first terminal carbon C at a first end of a carbon Cchain includes X and a second terminal carbon C at a second end of thecarbon chain includes Y, wherein X and Y independently include an aminegroup, a thiol group, a hydroxyl group, an isopropyl alcohol group, oran isopropyl amine group, except when n=1 then X and Y are bonded to thesame carbon C.

Specific examples of materials that may be used as the cross-linkingagent include the following:

Alternatively, instead of or in addition to the cross-linking agentbeing added to the photoresist composition, a coupling reagent is addedin some embodiments, in which the coupling reagent is added in additionto the cross-linking agent. The coupling reagent assists thecross-linking reaction by reacting with the groups on the hydrocarbonstructure in the polymer resin before the cross-linking reagent,allowing for a reduction in the reaction energy of the cross-linkingreaction and an increase in the rate of reaction. The bonded couplingreagent then reacts with the cross-linking agent, thereby coupling thecross-linking agent to the polymer resin.

Alternatively, in some embodiments in which the coupling reagent isadded to the photoresist without the cross-linking agent, the couplingreagent is used to couple one group from one of the hydrocarbonstructures in the polymer resin to a second group from a separate one ofthe hydrocarbon structures in order to cross-link and bond the twopolymers together. However, in such an embodiment the coupling reagent,unlike the cross-linking agent, does not remain as part of the polymer,and only assists in bonding one hydrocarbon structure directly toanother hydrocarbon structure.

In some embodiments, the coupling reagent has the following structure:

where R is a carbon atom, a nitrogen atom, a sulfur atom, or an oxygenatom; M includes a chlorine atom, a bromine atom, an iodine atom, —NO₂;—SO₃—; —H—; —CN; —NCO, —OCN; —CO₂—; —OH; —OR*, —OC(O)CR*; —SR,—SO₂N(R*)₂; —SO₂R*; SOR; —OC(O)R*; —C(O)OR*; —C(O)R*; —Si(OR*)₃;—Si(R*)₃; epoxy groups, or the like; and R* is a substituted orunsubstituted C1-C12 alkyl, C1-C12 aryl, C1-C12 aralkyl, or the like.Specific examples of materials used as the coupling reagent in someembodiments include the following:

The individual components of the photoresist are placed into a solventin order to aid in the mixing and dispensing of the photoresist. To aidin the mixing and dispensing of the photoresist, the solvent is chosenat least in part based upon the materials chosen for the polymer resinas well as the PACs. In some embodiments, the solvent is chosen suchthat the polymer resin and the PACs can be evenly dissolved into thesolvent and dispensed upon the layer to be patterned.

In some embodiments, the solvent is an organic solvent, and includes anysuitable solvent such as ketones, alcohols, polyalcohols, ethers, glycolethers, cyclic ethers, aromatic hydrocarbons, esters, propionates,lactates, lactic esters, alkylene glycol monoalkyl ethers, alkyllactates, alkyl alkoxypropionates, cyclic lactones, monoketone compoundsthat contain a ring, alkylene carbonates, alkyl alkoxyacetate, alkylpyruvates, lactate esters, ethylene glycol alkyl ether acetates,diethylene glycols, propylene glycol alkyl ether acetates, alkyleneglycol alkyl ether esters, alkylene glycol monoalkyl esters, or thelike.

Specific examples of materials that may be used as the solvent for thephotoresist include, acetone, methanol, ethanol, toluene, xylene,4-hydroxy-4-methyl-2-pentatone, tetrahydrofuran, methyl ethyl ketone,cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol,ethylene glycol monoacetate, ethylene glycol dimethyl ether, ethyleneglycol dimethyl ether, ethylene glycol methylethyl ether, ethyleneglycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolveacetate, diethylene glycol, diethylene glycol monoacetate, diethyleneglycol monomethyl ether, diethylene glycol diethyl ether, diethyleneglycol dimethyl ether, diethylene glycol ethylmethyl ether,diethethylene glycol monoethyl ether, diethylene glycol monobutyl ether,ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate,methyl 2-hydroxy-2-methylbutanate, methyl 3-methoxypropionate, ethyl3-methoxypropionate, methyl 3-ethoxypropionate, ethyl3-ethoxypropionate, methyl acetate, ethyl acetate, propyl acetate, butylacetate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate,propylene glycol, propylene glycol monoacetate, propylene glycolmonoethyl ether acetate, propylene glycol monomethyl ether acetate,propylene glycol monopropyl methyl ether acetate, propylene glycolmonobutyl ether acetate, propylene glycol monobutyl ether acetate,propylene glycol monomethyl ether propionate, propylene glycol monoethylether propionate, propylene glycol methyl ether acetate, propyleneglycol ethyl ether acetate, ethylene glycol monomethyl ether acetate,ethylene glycol monoethyl ether acetate, propylene glycol monomethylether, propylene glycol monoethyl ether, propylene glycol monopropylether, propylene glycol monobutyl ether, ethylene glycol monomethylether, ethylene glycol monoethyl ether, ethyl 3-ethoxypropionate, methyl3-methoxypropionate, methyl 3-ethoxypropionate, and ethyl3-methoxypropionate, β-propiolactone, β-butyrolactone, γ-butyrolactone,α-methyl-γ-butyrolactone, β-methyl-γ-butyrolactone, γ-valerolactone,γ-caprolactone, γ-octanoic lactone, α-hydroxy-γ-butyrolactone,2-butanone, 3-methylbutanone, pinacolone, 2-pentanone, 3-pentanone,4-methyl-2-pentanone, 2-methyl-3-pentanone, 4,4-dimethyl-2-pentanone,2,4-dimethyl-3-pentanone, 2,2,4,4-tetramethyl-3-pentanone, 2-hexanone,3-hexanone, 5-methyl-3-hexanone, 2-heptanone, 3-heptanone, 4-heptanone,2-methyl-3-heptanone, 5-methyl-3-heptanone, 2,6-dimethyl-4-heptanone,2-octanone, 3-octanone, 2-nonanone, 3-nonanone, 5-nonanone, 2-decanone,3-decanone, 4-decanone, 5-hexene-2-one, 3-pentene-2-one, cyclopentanone,2-methylcyclopentanone, 3-methylcyclopentanone,2,2-dimethylcyclopentanone, 2,4,4-trimethylcyclopentanone,cyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone,4-ethylcyclohexanone, 2,2-dimethylcyclohexanone,2,6-dimethylcyclohexanone, 2,2,6-trimethylcyclohexanone, cycloheptanone,2-methylcycloheptanone, 3-methylcycloheptanone, propylene carbonate,vinylene carbonate, ethylene carbonate, butylene carbonate,acetate-2-methoxyethyl, acetate-2-ethoxyethyl,acetate-2-(2-ethoxyethoxy)ethyl, acetate-3-methoxy-3-methylbutyl,acetate-1-methoxy-2-propyl, dipropylene glycol, monomethylether,monoethylether, monopropylether, monobutylether, monophenylether,dipropylene glycol monoacetate, dioxane, methyl pyruvate, ethylpyruvate, propyl pyruvate, methyl methoxypropionate, ethylethoxypropionate, n-methylpyrrolidone (NMP), 2-methoxyethyl ether(diglyme), ethylene glycol monomethyl ether, propylene glycol monomethylether, methyl propionate, ethyl propionate, ethyl ethoxy propionate,methylethyl ketone, cyclohexanone, 2-heptanone, cyclopentanone,cyclohexanone, ethyl 3-ethoxypropionate, propylene glycol methyl etheracetate (PGMEA), methylene cellosolve, 2-ethoxyethanol,N-methylformamide, N,N-dimethylformamide, N-methylformanilide,N-methylacetamide, N,N-dimethylacetamide, dimethylsulfoxide, benzylethyl ether, dihexyl ether, acetonylacetone, isophorone, caproic acid,caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate,ethyl benzoate, diethyl oxalate, diethyl maleate, phenyl cellosolveacetate, or the like.

As one of ordinary skill in the art will recognize, the materials listedand described above as examples of materials that may be used for thesolvent component of the photoresist are merely illustrative and are notintended to limit the embodiments. Rather, any suitable material thatdissolves the polymer resin and the PACs may be used to help mix andapply the photoresist. All such materials are fully intended to beincluded within the scope of the embodiments.

Additionally, while individual ones of the above described materials maybe used as the solvent for the photoresist, in other embodiments morethan one of the above described materials are used. For example, in someembodiments, the solvent includes a combination mixture of two or moreof the materials described. All such combinations are fully intended tobe included within the scope of the embodiments.

In addition to the polymer resins, the PACs, the solvents, thecross-linking agent, and the coupling reagent, some embodiments of thephotoresist also includes a number of other additives that assist thephotoresist to obtain high resolution. For example, some embodiments ofthe photoresist also includes surfactants in order to help improve theability of the photoresist to coat the surface on which it is applied.In some embodiments, the surfactants include nonionic surfactants,polymers having fluorinated aliphatic groups, surfactants that containat least one fluorine atom and/or at least one silicon atom,polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers,polyoxyethylene-polyoxypropylene block copolymers, sorbitan fatty acidesters, and polyoxyethylene sorbitan fatty acid esters.

Specific examples of materials used as surfactants in some embodimentsinclude polyoxyethylene lauryl ether, polyoxyethylene stearyl ether,polyoxyethylene cetyl ether, polyoxyethylene oleyl ether,polyoxyethylene octyl phenol ether, polyoxyethylene nonyl phenol ether,sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate,sorbitan monooleate, sorbitan trioleate, sorbitan tristearate,polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitanmonopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylenesorbitan trioleate, polyoxyethylene sorbitan tristearate, polyethyleneglycol distearate, polyethylene glycol dilaurate, polyethylene glycoldilaurate, polyethylene glycol, polypropylene glycol,polyoxyethylenestearyl ether, polyoxyethylene cetyl ether, fluorinecontaining cationic surfactants, fluorine containing nonionicsurfactants, fluorine containing anionic surfactants, cationicsurfactants and anionic surfactants, polyethylene glycol, polypropyleneglycol, polyoxyethylene cetyl ether, combinations thereof, or the like.

Another additive added to some embodiments of the photoresist is aquencher, which inhibits diffusion of the generated acids/bases/freeradicals within the photoresist. The quencher improves the resistpattern configuration as well as the stability of the photoresist overtime. In an embodiment, the quencher is an amine, such as a second loweraliphatic amine, a tertiary lower aliphatic amine, or the like. Specificexamples of amines include trimethylamine, diethylamine, triethylamine,di-n-propylamine, tri-n-propylamine, tripentylamine, diethanolamine, andtriethanolamine, alkanolamine, combinations thereof, or the like.

In some embodiments, an organic acid is used as the quencher. Specificembodiments of organic acids include malonic acid, citric acid, malicacid, succinic acid, benzoic acid, salicylic acid; phosphorous oxo acidand its derivatives, such as phosphoric acid and derivatives thereofsuch as its esters, phosphoric acid di-n-butyl ester and phosphoric aciddiphenyl ester; phosphonic acid and derivatives thereof such as itsester, such as phosphonic acid dimethyl ester, phosphonic aciddi-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester,and phosphonic acid dibenzyl ester; and phosphinic acid and derivativesthereof such as its esters, including phenylphosphinic acid.

Another additive added to some embodiments of the photoresist is astabilizer, which assists in preventing undesired diffusion of the acidsgenerated during exposure of the photoresist. In some embodiments, thestabilizer includes nitrogenous compounds, including aliphatic primary,secondary, and tertiary amines; cyclic amines, including piperidines,pyrrolidines, morpholines; aromatic heterocycles, including pyridines,pyrimidines, purines; imines, including diazabicycloundecene,guanidines, imides, amides, or the like. Alternatively, ammonium saltsare also be used for the stabilizer in some embodiments, includingammonium, primary, secondary, tertiary, and quaternary alkyl- andaryl-ammonium salts of alkoxides, including hydroxide, phenolates,carboxylates, aryl and alkyl sulfonates, sulfonamides, or the like.Other cationic nitrogenous compounds, including pyridinium salts andsalts of other heterocyclic nitrogenous compounds with anions, such asalkoxides, including hydroxide, phenolates, carboxylates, aryl and alkylsulfonates, sulfonamides, or the like, are used in some embodiments.

Another additive in some embodiments of the photoresist is a dissolutioninhibitor to help control dissolution of the photoresist duringdevelopment. In an embodiment bile-salt esters may be utilized as thedissolution inhibitor. Specific examples of dissolution inhibitors insome embodiments include cholic acid, deoxycholic acid, lithocholicacid, t-butyl deoxycholate, t-butyl lithocholate, and t-butyl-3-acetyllithocholate.

Another additive in some embodiments of the photoresist is aplasticizer. Plasticizers may be used to reduce delamination andcracking between the photoresist and underlying layers (e.g., the layerto be patterned). Plasticizers include monomeric, oligomeric, andpolymeric plasticizers, such as oligo- and polyethyleneglycol ethers,cycloaliphatic esters, and non-acid reactive steroidaly-derivedmaterials. Specific examples of materials used for the plasticizer insome embodiments include dioctyl phthalate, didodecyl phthalate,triethylene glycol dicaprylate, dimethyl glycol phthalate, tricresylphosphate, dioctyl adipate, dibutyl sebacate, triacetyl glycerine, orthe like.

A coloring agent is another additive included in some embodiments of thephotoresist. The coloring agent observers examine the photoresist andfind any defects that may need to be remedied prior to furtherprocessing. In some embodiments, the coloring agent is a triarylmethanedye or a fine particle organic pigment. Specific examples of materialsin some embodiments include crystal violet, methyl violet, ethyl violet,oil blue #603, Victoria Pure Blue BOH, malachite green, diamond green,phthalocyanine pigments, azo pigments, carbon black, titanium oxide,brilliant green dye (C. I. 42020), Victoria Pure Blue FGA (Linebrow),Victoria BO (Linebrow) (C. I. 42595), Victoria Blue BO (C. I. 44045),rhodamine 6G (C. I. 45160), benzophenone compounds, such as2,4-dihydroxybenzophenone and 2,2′,4,4′-tetrahydroxybenzophenone;salicylic acid compounds, such as phenyl salicylate and 4-t-butylphenylsalicylate; phenylacrylate compounds, such asethyl-2-cyano-3,3-diphenylacrylate, and2′-ethylhexyl-2-cyano-3,3-diphenylacrylate; benzotriazole compounds,such as 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole, and2-(3-t-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole;coumarin compounds, such as 4-methyl-7-diethylamino-1-benzopyran-2-one;thioxanthone compounds, such as diethylthioxanthone; stilbene compounds,naphthalic acid compounds, azo dyes, phthalocyanine blue, phthalocyaninegreen, iodine green, Victoria blue, crystal violet, titanium oxide,naphthalene black, Photopia methyl violet, bromphenol blue andbromcresol green; laser dyes, such as Rhodamine G6, Coumarin 500, DCM(4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H pyran)),Kiton Red 620, Pyrromethene 580, or the like. Additionally, one or morecoloring agents may be used in combination to provide the desiredcoloring.

Adhesion additives are added to some embodiments of the photoresist topromote adhesion between the photoresist and an underlying layer uponwhich the photoresist has been applied (e.g., the layer to bepatterned). In some embodiments, the adhesion additives include a silanecompound with at least one reactive substituent such as a carboxylgroup, a methacryloyl group, an isocyanate group and/or an epoxy group.Specific examples of the adhesion components include trimethoxysilylbenzoic acid, γ-methacryloxypropyl trimethoxy silane,vinyltriacetoxysilane, vinyltrimethoxysilane, γ-isocyanatepropyltriethoxy silane, γ-glycidoxypropyl trimethoxy silane,β-(3,4-epoxycyclohexyl)ethyl trimethoxy silane, benzimidazoles andpolybenzimidazoles, a lower hydroxyalkyl substituted pyridinederivative, a nitrogen heterocyclic compound, urea, thiourea, anorganophosphorus compound, 8-oxyquinoline, 4-hydroxypteridine andderivatives, 1,10-phenanthroline and derivatives, 2,2′-bipyridine andderivatives, benzotriazoles, organophosphorus compounds,phenylenediamine compounds, 2-amino-1-phenylethanol,N-phenylethanolamine, N-ethyldiethanolamine, N-ethylethanolamine andderivatives, benzothiazole, and a benzothiazoleamine salt having acyclohexyl ring and a morpholine ring,3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane,3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane,3-methacryloyloxypropyltrimethoxysilane, vinyl trimethoxysilane,combinations thereof, or the like.

Metal oxide nanoparticles are added to some embodiments of thephotoresist. In some embodiments, the photoresist includes one or moremetal oxides nanoparticles selected from the group consisting oftitanium dioxide, zinc oxide, zirconium dioxide, nickel oxide, cobaltoxide, manganese oxide, copper oxides, iron oxides, strontium titanate,tungsten oxides, vanadium oxides, chromium oxides, tin oxides, hafniumoxide, indium oxide, cadmium oxide, molybdenum oxide, tantalum oxides,niobium oxide, aluminum oxide, and combinations thereof. As used herein,nanoparticles are particles having an average particle diameter between1 and 100 nm.

Surface leveling agents are added to some embodiments of the photoresistto assist a top surface of the photoresist to be level, so thatimpinging light will not be adversely modified by an unlevel surface. Insome embodiments, surface leveling agents include fluoroaliphaticesters, hydroxyl terminated fluorinated polyethers, fluorinated ethyleneglycol polymers, silicones, acrylic polymer leveling agents,combinations thereof, or the like.

In some embodiments, the polymer resin and the PACs, along with anydesired additives or other agents, are added to the solvent forapplication. Once added, the mixture is then mixed in order to achieve ahomogenous composition throughout the photoresist to ensure that thereare no defects caused by uneven mixing or nonhomogenous composition ofthe photoresist. Once mixed together, the photoresist may either bestored prior to its usage or used immediately.

Once ready, the photoresist is applied onto the layer to be patterned,as shown in FIG. 2, such as the substrate 10 to form a photoresist layer15. In some embodiments, the photoresist is applied using a process suchas a spin-on coating process, a dip coating method, an air-knife coatingmethod, a curtain coating method, a wire-bar coating method, a gravurecoating method, a lamination method, an extrusion coating method,combinations of these, or the like. In some embodiments, the photoresistlayer 15 thickness ranges from about 10 nm to about 300 nm.

After the photoresist layer 15 has been applied to the substrate 10, apre-bake of the photoresist layer is performed in some embodiments tocure and dry the photoresist prior to radiation exposure (see FIG. 1).The curing and drying of the photoresist layer 15 removes the solventcomponent while leaving behind the polymer resin, the PACs, thecross-linking agent, and the other chosen additives. In someembodiments, the pre-baking is performed at a temperature suitable toevaporate the solvent, such as between about 50° C. and 250° C.,although the precise temperature depends upon the materials chosen forthe photoresist. The pre-baking is performed for a time sufficient tocure and dry the photoresist layer, such as between about 10 seconds toabout 10 minutes.

FIG. 3 illustrates a selective exposure of the photoresist layer to forman exposed region 50 and an unexposed region 15. In some embodiments,the exposure to radiation is carried out by placing the photoresistcoated substrate in a photolithography tool. The photolithography toolincludes a photomask 30, optics, an exposure radiation source to providethe radiation 45 for exposure, and a movable stage for supporting andmoving the substrate under the exposure radiation.

In some embodiments, the radiation source (not shown) supplies radiation45, such as ultraviolet light, to the photoresist layer 15 in order toinduce a reaction of the PACs, which in turn reacts with the polymerresin to chemically alter those regions of the photoresist layer towhich the radiation 45 impinges. In some embodiments the radiation iselectromagnetic radiation, such as g-line (wavelength of about 436 nm),i-line (wavelength of about 365 nm), ultraviolet radiation, farultraviolet radiation, extreme ultraviolet, electron beams, or the like.In some embodiments, the radiation source is selected from the groupconsisting of a mercury vapor lamp, xenon lamp, carbon arc lamp, a KrFexcimer laser light (wavelength of 248 nm), an ArF excimer laser light(wavelength of 193 nm), an F₂ excimer laser light (wavelength of 157nm), or a CO₂ laser-excited Sn plasma (extreme ultraviolet, wavelengthof 13.5 nm).

In some embodiments, optics (not shown) are used in the photolithographytool to expand, reflect, or otherwise control the radiation before orafter the radiation 45 is patterned by the photomask 30. In someembodiments the optics include one or more lenses, mirrors, filters, andcombinations thereof to control the radiation 45 along its path.

In an embodiment, the patterned radiation 45 is extreme ultravioletlight having a 13.5 nm wavelength, the PAC is a photoacid generator, thegroup to be decomposed is a carboxylic acid group on the hydrocarbonstructure, and a cross linking agent is used. The patterned radiation 45impinges upon the photoacid generator, the photoacid generator absorbsthe impinging patterned radiation 45. This absorption initiates thephotoacid generator to generate a proton (e.g., a H⁺ atom) within thephotoresist layer 15. When the proton impacts the carboxylic acid groupon the hydrocarbon structure, the proton reacts with the carboxylic acidgroup, chemically altering the carboxylic acid group and altering theproperties of the polymer resin in general. The carboxylic acid groupthen reacts with the cross-linking agent to cross-link with otherpolymer resins within the exposed region of the photoresist layer 15.

In some embodiments, the exposure of the photoresist layer 15 uses animmersion lithography technique. In such a technique, an immersionmedium (not shown) is placed between the final optics and thephotoresist layer, and the exposure radiation 45 passes through theimmersion medium.

After the photoresist layer 15 has been exposed to the exposureradiation 45, a post-exposure baking is performed in some embodiments toassist in the generating, dispersing, and reacting of the acid/base/freeradical generated from the impingement of the radiation 45 upon the PACsduring the exposure. Such thermal assistance helps to create or enhancechemical reactions which generate chemical differences between theexposed region 50 and the unexposed region 52 within the photoresistlayer 15. These chemical differences also cause differences in thesolubility between the exposed region 50 and the unexposed region 52. Insome embodiments, the post-exposure baking occurs at temperaturesranging from about 50° C. to about 160° C. for a period of between about20 seconds and about 120 seconds.

The inclusion of the cross-linking agent into the chemical reactionshelps the components of the polymer resin (e.g., the individualpolymers) react and bond with each other, increasing the molecularweight of the bonded polymer in some embodiments. In particular, aninitial polymer has a side chain with a carboxylic acid protected by oneof the groups to be removed/acid labile groups. The groups to be removedare removed in a de-protecting reaction, which is initiated by a protonH⁺ generated by, e.g., the photoacid generator during either theexposure process or during the post-exposure baking process. The H⁺first removes the groups to be removed/acid labile groups and anotherhydrogen atom may replace the removed structure to form a de-protectedpolymer. Once de-protected, a cross-linking reaction occurs between twoseparate de-protected polymers that have undergone the de-protectingreaction and the cross-linking agent in a cross-linking reaction. Inparticular, hydrogen atoms within the carboxylic groups formed by thede-protecting reaction are removed and the oxygen atoms react with andbond with the cross-linking agent. This bonding of the cross-linkingagent to two polymers bonds the two polymers not only to thecross-linking agent but also bonds the two polymers to each otherthrough the cross-linking agent, thereby forming a cross-linked polymer.

By increasing the molecular weight of the polymers through thecross-linking reaction, the new cross-linked polymer becomes lesssoluble in conventional organic solvent negative resist developers.

On the other hand, photoresist developers 57 according to someembodiments of the present disclosure dissolve the cross-linked,radiation-exposed portions 50 of the photoresist layer 15.

In some embodiments, the photoresist developer 57 includes a majorsolvent, an acid or a base, and a chelate. In some embodiments, theconcentration of the major solvent is from about 60 wt. % to about 99wt. % based on the total weight of the photoresist developer. The acidor base concentration is from about 0.001 wt. % to about 20 wt. % basedon the total weight of the photoresist developer. In certainembodiments, the acid or base concentration in the developer is fromabout 0.01 wt. % to about 15 wt. % based on the total weight of thephotoresist developer. The chelate concentration is from about 0.001 wt.% to about 20 wt. % of the total weight of the photoresist developer. Incertain embodiments, the concentration of the chelate ranges from about0.01 wt. % to about 15 wt. % based on the total weight of thephotoresist developer.

In some embodiments, the major solvent has Hansen solubility parametersof 15<δ_(d)<25, 10<δ_(p)<25, and 6<δ_(h)<30. The units of the Hansensolubility parameters are (Joules/cm³)^(1/2) or, equivalently, MPa^(1/2)and are based on the idea that one molecule is defined as being likeanother if it bonds to itself in a similar way. δ_(d) is the energy fromdispersion forces between molecules. δ_(p) is the energy from dipolarintermolecular force between the molecules. δ_(h) is the energy fromhydrogen bonds between molecules. The three parameters, δ_(d), δ_(p),and δ_(h), can be considered as coordinates for a point in threedimensions, known as the Hansen space. The nearer two molecules are inHansen space, the more likely they are to dissolve into each other.

Solvents having the desired Hansen solubility parameters includedimethyl sulfoxide, acetone, ethylene glycol, methanol, ethanol,propanol, propanediol, water, 4-methyl-2-pentanone, hydrogen peroxide,isopropanol, and butyldiglycol.

In some embodiments, the acid has an acid dissociation constant, pK_(a),of −15<pK_(a)<4. In some embodiments, the base has a pK_(a) of40>pK_(a)>9.5. The acid dissociation constant, pK_(a), is thelogarithmic constant of the acid dissociation constant K_(a). K_(a) is aquantitative measure of the strength of an acid in solution. K_(a) isthe equilibrium constant for the dissociation of a generic acidaccording to the equation HA+H₂O↔A⁻+H₃O⁺, where HA dissociates into itsconjugate base, A⁻, and a hydrogen ion which combines with a watermolecule to form a hydronium ion. The dissociation constant can beexpressed as a ratio of the equilibrium concentrations:

$K_{a\mspace{14mu} =}{\frac{\left\lbrack A^{-} \right\rbrack\left\lbrack {H_{3}O^{+}} \right\rbrack}{\lbrack{HA}\rbrack\left\lbrack {H_{2}O} \right\rbrack}.}$In most cases, the amount of water is constant and the equation can besimplified to HA↔A⁻+H⁺, and

$K_{a} = {\frac{\left\lbrack A^{-} \right\rbrack\left\lbrack H^{+} \right\rbrack}{\lbrack{HA}\rbrack}.}$The logarithmic constant, pK_(a) is related to K_(a) by the equationpK_(a)=−log₁₀ (K_(a)). The lower the value of pK_(a) the stronger theacid. Conversely, the higher the value of pK_(a) the stronger the base.

In some embodiments, suitable acids for the photoresist developer 57include an organic acid selected from the group consisting ofethanedioic acid, methanoic acid, 2-hydroxypropanoic acid,2-hydroxybutanedioic acid, citric acid, uric acid,trifluoromethanesulfonic acid, benzenesulfonic acid, ethanesulfonicacid, methanesulfonic acid, oxalic acid, maleic acid, carbonic acid,oxoethanoic acid, 2-hydroxyethanoic acid, propanedioic acid, butanedioicacid, 3-oxobutanoic acid, hydroxylamine-o-sulfonic acid,formamidinesulfinic acid, methylsulfamic acid, sulfoacetic acid,1,1,2,2-tetrafluoroethanesulfonic acid, 1,3-propanedisulfonic acid,nonafluorobutane-1-sulfonic acid, 5-sulfosalicylic acid, andcombinations thereof. In some embodiments, the acid is an inorganic acidselected from the group consisting of nitric acid, sulfuric acid,hydrochloric acid, and combinations thereof.

In some embodiments, suitable bases for the photoresist developer 57include an organic base selected from the group consisting ofmonoethanolamine, monoisopropanolamine, 2-amino-2-methyl-1-propanol,1H-benzotriazole, 1,2,4-triazole, 1,8-diazabicycloundec-7-ene,tetrabutylammonium hydroxide, tetramethylammonium hydroxide, ammoniumhydroxide, ammonium sulfamate, ammonium carbamate, tetraethylammoniumhydroxide, tetrapropylammonium hydroxide, and combinations thereof.

In some embodiments, the chelate is selected from the group consistingof ethylenediaminetetraacetic acid (EDTA),ethylenediamine-N,N′-disuccinic acid (EDDS),diethylenetriaminepentaacetic acid (DTPA), polyaspartic acid,trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid monohydrate,ethylenediamine, and combinations thereof, or the like.

In an embodiment, the photoresist developer 57 includes an additionalsolvent. In some embodiments, the additional solvent includes water;hexane, heptane, octane, toluene, xylene, dichloromethane, chloroform,carbon tetrachloride, trichloroethylene, and like hydrocarbon solvents;critical carbon dioxide, methanol, ethanol, propanol, butanol, and likealcohol solvents; diethyl ether, dipropyl ether, dibutyl ether, ethylvinyl ether, dioxane, propylene oxide, tetrahydrofuran, cellosolve,methyl cellosolve, butyl cellosolve, methyl carbitol, diethylene glycolmonoethyl ether and like ether solvents; acetone, methyl ethyl ketone,methyl isobutyl ketone, isophorone, cyclohexanone and like ketonesolvents; methyl acetate, ethyl acetate, propyl acetate, butyl acetateand like ester solvents; pyridine, formamide, and N,N-dimethyl formamideor the like. In an embodiment, the concentration of the additionalsolvent is from about 1 wt. % to about 40 wt. % based on the totalweight of the developer.

In some embodiments, the photoresist developer 57 includes hydrogenperoxide in a concentration of up to about 10 wt. % based on the totalweight of the developer.

In some embodiments, the photoresist developer 57 includes up to about 1wt. % of a surfactant to increase the solubility and reduce the surfacetension on the substrate. In some embodiments, the surfactant isselected from the group consisting of alkylbenzenesulfonates, ligninsulfonates, fatty alcohol ethoxylates, and alkylphenol ethoxylates. Insome embodiments, the surfactant is selected from the group consistingof sodium stearate, 4-(5-dodecyl) benzenesulfonate, ammonium laurylsulfate, sodium lauryl sulfate, sodium laureth sulfate, sodium myrethsulfate, dioctyl sodium sulfosuccinate, perfluorooctanesulfonate,perfluorobutanesulfonate, alkyl-aryl ether phosphate, alkyl etherphosphates, sodium lauroyl sarcosinate, perfluoronononanoate,perfluorooctanoate, octenidine dihydrochloride, cetrimonium bromide,cetylpyridinium chloride, benzalkonium chloride, benzethonium chloride,dimethyldioctadecylammonium chloride, dioctadecyldimethylammoniumbromide, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate,cocamidopropyl hydroxysultaine, cocamidopropyl betaine,phospholipidsphosphatidylserine, phosphatidylethanolamine,phosphatidylcholine, sphingomyelins, octaethylene glycol monodecylether, pentaethylene glycol monodecyl ether, polyethoxylated tallowamine, cocamide monoethanolamine, cocamide diethanolamine, glycerolmonostearate, glycerol monolaurate, sorbitan monolaurate, sorbitanmonostearate, sorbitan tristearate, and combinations thereof.

In some embodiments, the developer 57 is applied to the photoresistlayer 15 using a spin-on process. In the spin-on process, the developer57 is applied to the photoresist layer 15 from above the photoresistlayer 15 while the photoresist coated substrate is rotated, as shown inFIG. 4. In some embodiments the developer 57 is supplied at a rate ofbetween about 5 ml/min and about 800 ml/min, while the photoresistcoated substrate 10 is rotated at a speed of between about 100 rpm andabout 2000 rpm. In some embodiments, the developer is at a temperatureof between about 10° C. and about 80° C. The development operationcontinues for between about 30 seconds to about 10 minutes in someembodiments.

While the spin-on operation is one suitable method for developing thephotoresist layer 15 after exposure, it is intended to be illustrativeand is not intended to limit the embodiment. Rather, any suitabledevelopment operations, including dip processes, puddle processes, andspray-on methods, may alternatively be used. All such developmentoperations are included within the scope of the embodiments.

During the development process, the developer 57 dissolves the radiationexposed regions 50 of the cross-linked negative resist, exposing thesurface of the substrate 10, as shown in FIG. 5, and leaving behindwell-defined unexposed photoresist regions 52, having improveddefinition than provided by conventional negative photoresistphotolithography.

After the developing operation S150, remaining developer is removed fromthe patterned photoresist covered substrate. The remaining developer isremoved using a spin-dry process in some embodiments, although anysuitable removal technique may be used. After the photoresist layer 15is developed, and the remaining developer is removed, additionalprocessing is performed while the patterned photoresist layer 52 is inplace. For example, an etching operation, using dry or wet etching, isperformed in some embodiments, to transfer the pattern of thephotoresist layer 52 to the underlying substrate 10, forming recesses55″ as shown in FIG. 6. The substrate 10 has a different etch resistancethan the photoresist layer 15. In some embodiments, the etchant is moreselective to the substrate 10 than the photoresist layer 15.

In some embodiments, the substrate 10 and the photoresist layer 15contain at least one etching resistance molecule. In some embodiments,the etching resistant molecule includes a molecule having a low Onishinumber structure, a double bond, a triple bond, silicon, siliconnitride, titanium, titanium nitride, aluminum, aluminum oxide, siliconoxynitride, combinations thereof, or the like.

In some embodiments, a layer to be patterned 60 is disposed over thesubstrate prior to forming the photoresist layer, as shown in FIG. 7. Insome embodiments, the layer to be patterned 60 is a metallization layeror a dielectric layer, such as a passivation layer, disposed over ametallization layer. In embodiments where the layer to be patterned 60is a metallization layer, the layer to be patterned 60 is formed of aconductive material using metallization processes, and metal depositiontechniques, including chemical vapor deposition, atomic layerdeposition, and physical vapor deposition (sputtering). Likewise, if thelayer to be patterned 60 is a dielectric layer, the layer to bepatterned 60 is formed by dielectric layer formation techniques,including thermal oxidation, chemical vapor deposition, atomic layerdeposition, and physical vapor deposition.

The photoresist layer 50 is subsequently selectively exposed to actinicradiation 45 to form exposed regions 50 and unexposed regions 52 in thephotoresist layer, as shown in FIG. 8, and described herein in relationto FIG. 3. As explained herein the photoresist is a negativephotoresist, wherein polymer crosslinking occurs in the exposed regions50 in some embodiments.

As shown in FIG. 9, the exposed photoresist regions 50 are developed bydispensing developer 57 from a dispenser 62 to form a pattern ofphotoresist openings 55, as shown in FIG. 10. The development operationis similar to that explained with reference to FIGS. 4 and 5, herein.

Then as shown in FIG. 11, the pattern 55 in the photoresist layer 15 istransferred to the layer to be patterned 60 using an etching operationand the photoresist layer is removed, as explained with reference toFIG. 6 to form pattern 55″ in the layer to be patterned 60.

In some embodiments, the selective exposure of the photoresist layer 15to form exposed regions 50 and unexposed regions 52 is performed usingextreme ultraviolet lithography. In an extreme ultraviolet lithographyoperation a reflective photomask 65 is used to form the patternedexposure light, as shown in FIG. 12. The reflective photomask 65includes a low thermal expansion glass substrate 70, on which areflective multilayer 75 of Si and Mo is formed. A capping layer 80 andabsorber layer 85 are formed on the reflective multilayer 75. A rearconductive layer 90 is formed on the back side of the low thermalexpansion substrate 70. In extreme ultraviolet lithography, extremeultraviolet radiation 95 is directed towards the reflective photomask 65at an incident angle of about 6°. A portion 97 of the extremeultraviolet radiation is reflected by the Si/Mo multilayer 75 towardsthe photoresist coated substrate 10, while the portion of the extremeultraviolet radiation incident upon the absorber 85 is absorbed by thephotomask. In some embodiments, additional optics, including mirrors arebetween the reflective photomask 65 and the photoresist coatedsubstrate.

The novel photoresist developer compositions and negative photoresistphotolithography techniques according to the present disclosure providehigher semiconductor device feature density with reduced defects in ahigher efficiency process than conventional developers and techniques.

An embodiment of the disclosure is a photoresist developer, including asolvent having Hansen solubility parameters of 15<δ_(d)<25, 10<δ_(p)<25,and 6<δ_(h)<30; an acid having an acid dissociation constant, pKa, of−15<pKa<4, or a base having a pKa of 40>pKa>9.5; and a chelate. In anembodiment, the concentration of the solvent is from about 60 wt. % toabout 99 wt. % based on the total weight of the photoresist developer.In an embodiment, the concentration of the acid or base is from about0.001 wt. % to about 20 wt. % based on the total weight of thephotoresist developer. In an embodiment, the concentration of thechelate is 0.001 wt. % to about 20 wt. % based on the total weight ofthe photoresist developer. In an embodiment, the photoresist developerincludes a surfactant. In an embodiment, the concentration of thesurfactant is from about 0.001 wt. % to about 1 wt. % based on the totalweight of the photoresist developer. In an embodiment, the photoresistdeveloper includes an additional solvent. In an embodiment, theconcentration of the additional solvent is from about 1 wt. % to about40 wt. % based on the total weight of the photoresist developer. In anembodiment, the photoresist developer includes hydrogen peroxide.

In another embodiment of the disclosure, a method of forming a patternin a photoresist includes forming a photoresist layer on a substrate,and selectively exposing the photoresist layer to actinic radiation toform a latent pattern. The latent pattern is developed by applying adeveloper to the selectively exposed photoresist layer to form apattern. The developer includes a solvent having Hansen solubilityparameters of 15<δ_(d)<25, 10<δ_(p)<25, and 6<δ_(h)<30; an acid havingan acid dissociation constant, pKa, of −15<pKa<4, or a base having a pKaof 40>pKa>9.5; and a chelate. In an embodiment, the concentration of thesolvent is from about 60 wt. % to about 99 wt. % based on the totalweight of the photoresist developer, the concentration of the acid orbase is from about 0.001 wt. % to about 20 wt. % based on the totalweight of the photoresist developer, and the concentration of thechelate is 0.001 wt. % to about 20 wt. % based on the total weight ofthe photoresist developer. In an embodiment, the developer is at atemperature of about 25° C. to about 75° C. during the developing. In anembodiment, the photoresist layer is heated before selectively exposingthe photoresist layer to actinic radiation. In an embodiment, thephotoresist layer is heated after selectively exposing the photoresistlayer to actinic radiation and before developing the photoresist layer.In an embodiment, a portion of the photoresist layer selectively exposedto actinic radiation is removed from the photoresist layer during thedeveloping, thereby exposing a portion of the substrate.

In another embodiment of the disclosure, a method of forming a patternin a photoresist includes forming a photoresist layer on a substrate.The photoresist layer is selectively exposed to actinic radiationthereby crosslinking the photoresist layer in a region of thephotoresist layer exposed to the actinic radiation. The region of thephotoresist exposed to actinic radiation is removed by developing thephotoresist layer by applying a liquid developer to the photoresistlayer. In an embodiment, the developer includes a solvent having Hansensolubility parameters of 15<δ_(d)<25, 10<δ_(p)<25, and 6<δ_(h)<30; anacid having an acid dissociation constant, pKa, of −15<pKa<4, or a basehaving a pKa of 40>pKa>9.5; and a chelate. In an embodiment, the methodincludes heating the photoresist layer before selectively exposing thephotoresist layer to actinic radiation, and heating the photoresistlayer after selectively exposing the photoresist layer to actinicradiation and before developing the photoresist layer. In an embodiment,the concentration of the solvent is from about 60 wt. % to about 99 wt.% based on the total weight of the photoresist developer, theconcentration of the acid or base is from about 0.001 wt. % to about 20wt. % based on the total weight of the photoresist developer, and theconcentration of the chelate is 0.001 wt. % to about 20 wt. % based onthe total weight of the photoresist developer. In an embodiment, thedeveloper includes an additional solvent and a surfactant.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A photoresist developer, comprising: a firstsolvent having Hansen solubility parameters of 15<δ_(d)<25, 10<δ_(p)<25,and 6<δ_(h)<30; a base having a pKa of 40>pKa>9.5, wherein the base isselected from the group consisting of 2-amino-2-methyl-1-propanol,1H-benzotriazole, 1,2,4-triazole, 1,8-diazabicycloundec-7-ene, ammoniumsulfamate, ammonium carbamate, and combinations thereof; and a chelateselected from a group consisting of ethylenediamine-N,N′-disuccinic acid(EDDS), diethylenetriaminepentaacetic acid (DTPA), polyaspartic acid,trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid monohydrate, andcombinations thereof, wherein the concentration of the chelate is 0.001wt. % to 20 wt. % based on the total weight of the photoresistdeveloper.
 2. The photoresist developer of claim 1, wherein theconcentration of the first solvent is from 60 wt. % to 99 wt. % based onthe total weight of the photoresist developer.
 3. The photoresistdeveloper of claim 1, wherein the concentration of the base is from0.001 wt. % to 20 wt. % based on the total weight of the photoresistdeveloper.
 4. The photoresist developer of claim 1, further comprising asurfactant.
 5. The photoresist developer of claim 4, wherein theconcentration of the surfactant is from 0.001 wt. % to 1 wt. % based onthe total weight of the photoresist developer.
 6. The photoresistdeveloper of claim 1, further comprising a second solvent different fromthe first solvent.
 7. The photoresist developer of claim 6, wherein theconcentration of the additional solvent is from 1 wt. % to 40 wt. %based on the total weight of the developer.
 8. The photoresist developerof claim 1, further comprising hydrogen peroxide.
 9. The photoresistdeveloper of claim 1, wherein the first solvent comprises at least onefrom the group consisting of dimethyl sulfoxide, acetone, ethyleneglycol, methanol, ethanol, propanol, propanediol, water,4-methyl-2-pentanone, hydrogen peroxide, isopropanol, and butyldiglycol.10. A method of forming a pattern in a photoresist, comprising: forminga photoresist layer on a substrate; selectively exposing the photoresistlayer to actinic radiation to cross-link exposed portions of thephotoresist layer and form a latent pattern; and developing the latentpattern by applying a developer to the selectively exposed photoresistlayer to form a pattern, wherein the developer comprises: a firstsolvent having Hansen solubility parameters of 15<δ_(d)<25, 10<δ_(p)<25,and 6<δ_(h)<30; an acid having an acid dissociation constant, pKa, of−15<pKa<4, or a base having a pKa of 40>pKa>9.5; and a chelate selectedfrom a group consisting of ethylenediamine-N,N′-disuccinic acid (EDDS),diethylenetriaminepentaacetic acid (DTPA), polyaspartic acid,trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid monohydrate, andcombinations thereof, wherein the concentration of the chelate is 0.001wt. % to 20 wt. % based on the total weight of the photoresistdeveloper.
 11. The method according to claim 10, wherein theconcentration of the first solvent is from about 60 wt. % to about 99wt. % based on the total weight of the photoresist developer, and theconcentration of the acid or base is from about 0.001 wt. % to about 20wt. % based on the total weight of the photoresist developer.
 12. Themethod according to claim 10, wherein the developer is at a temperatureof about 25° C. to about 75° C. during the developing.
 13. The methodaccording to claim 10, further comprising a first heating of thephotoresist layer before the selectively exposing the photoresist layerto actinic radiation.
 14. The method according to claim 13, furthercomprising a second heating of the photoresist layer after theselectively exposing the photoresist layer to actinic radiation andbefore the developing the latent pattern.
 15. The method according toclaim 10, wherein a portion of the photoresist layer selectively exposedto actinic radiation to cross-link exposed portions of the photoresistlayer and form a latent pattern is removed from the photoresist layerduring the developing, thereby exposing a portion of the substrate. 16.A method of forming a pattern in a photoresist, comprising: forming aphotoresist layer on a substrate; selectively exposing the photoresistlayer to actinic radiation thereby crosslinking the photoresist layer ina region of the photoresist layer exposed to the actinic radiation; andremoving the region of the photoresist exposed to actinic radiation bydeveloping the photoresist layer by applying a liquid developer to thephotoresist layer, wherein the developer comprises a chelate selectedfrom a group consisting of ethylenediamine-N,N′-disuccinic acid (EDDS),diethylenetriaminepentaacetic acid (DTPA), polyaspartic acid,trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid monohydrate, andcombinations thereof, wherein the concentration of the chelate is 0.001wt. % to 20 wt. % based on the total weight of the photoresistdeveloper.
 17. The method according to claim 16, wherein the developercomprises: a solvent having Hansen solubility parameters of 15<δ_(d)<25,10<δ_(p)<25, and 6<δ_(h)<30; and an acid having an acid dissociationconstant, pKa, of −15<pKa<4, or a base having a pKa of 40>pKa>9.5. 18.The method according to claim 17, wherein the concentration of thesolvent is from about 60 wt. % to about 99 wt. % based on the totalweight of the photoresist developer, and the concentration of the acidhaving an acid dissociation constant, pKa, of −15<pKa<4 or base having apKa of 40>pKa>9.5 is from about 0.001 wt. % to about 20 wt. % based on atotal weight of the photoresist developer.
 19. The method according toclaim 18, wherein the developer further comprises an additional solventand a surfactant.
 20. The method according to claim 16, furthercomprising: a first heating of the photoresist layer before theselectively exposing the photoresist layer to actinic radiation; and asecond heating of the photoresist layer after the selectively exposingthe photoresist layer to actinic radiation and before the developing thephotoresist layer.